1. Field of the Invention
The present invention relates to a terminal connected to an electrode of a piezoelectric element, a wiring member having the terminal, and a head suspension having the wiring member.
2. Description of Related Art
Recent magnetic disk drives frequently employ a dual actuator system that uses, in addition to a voice coil motor to turn a head suspension as a whole, a piezoelectric element to minutely turn a head of the head suspension.
The piezoelectric element is arranged between a base plate and a load beam in the head suspension, and in proportion to a voltage applied thereto, deforms to precisely move the head at a front end of the load beam relative to the base plate.
To attach the piezoelectric element to the head suspension, the head suspension is generally provided with an actuator base having an opening in which the piezoelectric element is accommodated.
The head suspension has a flexure. i.e., a wiring member having a terminal that is connected to the piezoelectric element in the actuator base for power feeding. The terminal extends from the flexure along the actuator base so that a terminal main part of the terminal is positioned above the opening of the actuator base and is connected to the piezoelectric element with a conductive adhesive.
The piezoelectric element is frequently thinner than the actuator base, and when accommodated in the opening of the actuator base, creates a gap with respect to the terminal main part. The gap must be bridged by increasing the amount of the conductive adhesive to connect the terminal and piezoelectric element to each other.
The increased amount of the conductive adhesive raises costs and causes the conductive adhesive to ooze. In addition, the conductive adhesive used here is not a structural adhesive, and therefore, is inappropriate to form a bridge between the piezoelectric element and the terminal.
To deal with the problems, Japanese Unexamined Patent Application Publication No. 2002-208124 discloses a technique of forming a bend in a terminal wiring part of the terminal. The terminal wiring part extends from the flexure to the terminal main part, and the bend in the terminal wiring part brings the terminal main part closer to the piezoelectric element.
This related art, however, is unable to stabilize an angle of the bend and unable to secure parallelism between the terminal main part and the piezoelectric element, and therefore, is improper for actual use.
The flexure attached to the head suspension includes a supportive metal layer, an insulating layer formed on the supportive metal layer, and a wiring layer formed on the insulating layer. For the benefit of manufacturing, the terminal of the flexure to be connected to the piezoelectric element is preferred to have the same layered structure as the flexure.
In regard to the terminal of the flexure, the terminal wiring part is required to have low rigidity in an in-plane direction because the terminal wiring part must quickly follow deformation of the piezoelectric element to which the terminal is connected. The terminal wiring part is laid between the actuator base and the piezoelectric element and the actuator base functions as the grounding of the piezoelectric element, and therefore, the supportive metal layer of the terminal must be isolated from the actuator base to avoid a short circuit between them.
To realize the low rigidity and short-circuit prevention of the terminal, the related art removes the supportive metal layer from the terminal wiring part.
With the supportive metal layer removed, the related art bends the insulating layer (made of resin) and very thin wiring layer of the terminal wiring part to form the bend in the terminal. This is the reason why the bend of the related art is unable to stabilize a bend angle or secure parallelism between the terminal main part and the piezoelectric element.